About 110 species: mainly in tropical and subtropical Asia, but a few species also in temperate Asia, Europe, and North America; 54 species (40 endemic) in China; one additional species (endemic, not included in the key) is of uncertain position.

Both surfaces of leaves or only abaxially tomentose, or both surfaces or adaxially with squarrose or capitate-stalked glandular hairs, or adaxially glabrous and green when dry; subshrubs or perennial herbs